


Sing like the birdies sing, tweet tweet tweet tweet

by Drew-drew (Our_Nom_De_Plume), Lifeofalternative (Our_Nom_De_Plume)



Category: Undertale (Video Game)
Genre: Cloaca, Condoms, Explicit Sexual Content, First Time Bottoming, Gay Sex, M/M, Not Suitable/Safe For Work, Safer Sex, Sex
Language: English
Status: Completed
Published: 2019-11-09
Updated: 2019-11-09
Packaged: 2021-01-26 17:33:38
Rating: Explicit
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 1,073
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/21377878
Author URL: https://archiveofourown.org/users/Our_Nom_De_Plume/pseuds/Drew-drew, https://archiveofourown.org/users/Our_Nom_De_Plume/pseuds/Lifeofalternative
Summary: (Pairing: Swapmoss)It's not every day your boyfriend turns out to have a cloaca, but when you're in bed with him, you betcha you'll grab the lube and stick on a condom, because it's gonna be a fun ride.
Relationships: Sans/Sans (Undertale)
Comments: 7
Kudos: 63





	Sing like the birdies sing, tweet tweet tweet tweet

**Author's Note:**

> Placeholder summary
> 
> Idk why I didn't put this in my smut stash but I think I forgot and just left it as something seperate
> 
> And I heard from the grapevine that today is Dreamswap's 3rd anniversary
> 
> happy birthday dreamswap have some porn

It's unlike himself to really be in this position. He's talked about it a lot - it's a discussion he practically gets into mindlessly, but when it comes down to it, it's really a thing he hasn't tried before.

Well, not _ever_ tried, as innocent curiosity and exceptionally rough days leave him to explore, figuring out what he likes, what he doesn't, getting used to his anatomy, but doing all this with a partner? Never has he ever.

Especially one he's not exactly made to handle. He's made for other cloacas or perhaps another monster - or human, he's not picky - with a smaller dick. _Not for someone hung like a centaur._

He's lying down on a bunch of pillows on his back, hands on his knees while Cross sitting on his legs, lubing up his dick and rolling a condom over it and jellying himself up more. It's intimidatingly large - perhaps not by other's standards, but he's never taken anything inside besides his fingers, and 6 inches is awfully deep for his cloaca. He's glad that Cross is taking every precaution to make sure it's all a smooth ride - lots of foreplay, maybe a little more lube then perhaps necessary, and safe sex. He isn't exactly used to cum inside him and figures it's better to leave creampies when he's more used to something practically tearing his cloaca in half.

Cross feels the outside of his cloaca with his- still lubed- fingers. It makes him shudder, as he's very much wet and burning down there worse then a fire elemental. An hour long of foreplay - first just kissing, then a massage, before feeling down there... Then Cross softly licking and kissing the organ, then opening him up with gentle fingering. His entire cloaca is sensitive, no specific points more sensitive then the other because it's _all sensitive to anything._

"Nightmare..." Cross' soft murmur gets his attention, "Do you feel ready?"

He whimpers. "If we wait any longer, I'll go crazy."

Cross nods, before getting into a position over Nightmare, grabbing the base of his dick to guide it to his cloaca. Nightmare spreads his legs a little more to allow Cross more room, seeing Cross' genitalia rub against his winking hole. It's teasing, but Nightmare doesn't complain and in a moment Cross enters.

He's met with the feeling of something firm but soft, sinking into his cloaca and stretching it to just a small burning, covered by surges of pleasure down his spine. Cross stops midway to make sure he's fine, but continues when he finds no red flags.

Only when it's fully shealthed in did he start to feel an uncomfortable full feeling, but sighed with relief as he couldn't push in anymore.

Cross nuzzles Nightmare, smooching his nose (which is as close to his mouth he is going to get without awkwardly bending down). "You feel nice."

"And you're big," Nightmare huffed, causing Cross to flush a bright purple, before muttering 'I'm not big...', though whether he said it to be modest or that he truely didn't think he was big, Nightmare didn't know - but he didn't further tease Cross, instead relaxing as best he could as his cloaca created more slick, clenching down on Cross' shaft. 

It was clear as day Cross was eager to get the pleasure going, for he was shifting and his hips were lightly twitching, but he kept patient.

But dear god, when Nightmare's cloaca clenched down, Cross' patience wore thin and he started moving. Thankfully, Nightmare didn't feel as uncomfortable of a stretch as when they started, Cross' thrusting pulling a pleasured coo out of him. The monochrome skeleton pulled out slowly - though not all the way out, Nightmare was just too delectable to exit - before pushing back in. It was a nice, relaxing pace that Nightmare easily melted into.

However as time went on, Cross started growing more impatient. Cross had ended up wrapping his arms around Nightmare as he continued to rock into his core, trying his best to keep his pace steady, but the delectable, squelch sounds of Nightmare's cloaca when he trusts were too good to resist, and without warning he thrusted a bit harsher. Cross wasn't much of a vocalist, but those deep grunts were definitely something to be heard, even over Nightmare's ecstatic squack. It left Nightmare starting to have trouble thinking from the continuous pleasure coursing through his body, though a growing feeling, one that got more apparent the more Cross thrusted, kept him still in this realm. As Cross grabbed Nightmare's hips and kept going, faster and a bit deeper, Nightmare let out a breathless coo as his cum shot from his cloaca onto Cross' length, pearly white and reminiscent to watered down glue had it not been for the salty-sweet aroma of it. After a few more shudders and squeezes on Cross' dick, he grunted out "I'm gonna cum quickly if you keep doing that,"

"Go right ahead," Nightmare breathed out, feeling more sensitive after orgasm and gasping at every movement of Cross' cock inside of him. It seemed to spur him onward, for after a few more thrusts on Cross' part, he let a deep moan and buried himself into Nightmare, finishing himself off.

They stayed like that for a while, hands around each other as they catch their breath, before Cross finally said something.

"Hey, can I pull out now? It feels weird with the condom on..." He sheepishly mentioned.

Nightmare didn't notice what a death grip he had on Cross, but he awkwardly put his arms to his sides. "Sure."

Cross reached down and brushed his cloaca - Nightmare emitting a soft sigh in pleasure - as he grabbed the edge of the condom and pulled out. His cum pooled at the end of his penis, and he hissed as he got it off and tied it, before promptly throwing it away in the mini trashcan they put beforehand. With that out of the way, Cross gets up and grabs some blankets from the closet floor. He nudges Nightmare to scoot, then gets onto the bed and puts the plush blankets over themselves.

Now they're laying down properly, facing each other. Nightmare has his eyes closed and Cross is staring at him.

"You think Error's gonna kill us when he gets back?"

Nightmare opens his eyes and stares back at Cross.

"Totally. He'll make us clean the sheets even though it's his laundry week."

"Worth it."

**Author's Note:**

> Dream also has cloaca, you're all welcome.


End file.
